On Wednesday, 1 September 2021 at 22:51:40 UTC, Per Nordlöw wrote:
Can somebody explain the need for
```d
private template isSame(alias a, alias b)
{
static if (!is(typeof(&a && &b)) // at least one is an
rvalue
&& __traits(compiles, { enum isSame = a == b; }))
// c-t comparable
{
enum isSame = a == b;
}
else
{
enum isSame = __traits(isSame, a, b);
}
}
```
when there is already
```d
__traits(isSame, a, b)
```
?
Are there any cases where
```d
__traits(isSame, a, b)
```
doesn't have the same value as
```d
a == b
```
provided the static if expression above is true.
the traits does not work on literals passed by
_AliasTemplateParameter_.
```d
enum isSame1(alias a, alias b) = a == b;
enum isSame2(alias a, alias b) = __traits(isSame, a, b);
pragma(msg, isSame1!(0, 0)); // true
pragma(msg, isSame2!(0, 0)); // false
```
This looks a bit like a bug, because `__traits(isSame, 0, 0)`
yields `true`
